For asymptotically flat spacetimes, the asymptotic symmetry groups at null infinity are the Bondi-Metzner-Sachs (BMS) groups [1]}, [2]}, which in dimensions three [3]} and four are infinite dimensional groups. After a long hiatus since its original discovery in the context of four dimensional spacetimes in the late 1960s, the theoretical physics community has now woken up to the realisation that the BMS group should be omnipresent in the discussions of scattering theory in quantum field theories defined in asymptotically flat spacetimes. Following the lead of Strominger [4]}, a large volume of literature has built up linking the BMS group with soft theorems and memory effects in a triangle of relations. We refer the interested reader to [5]} for a detailed discussion on these issues and related references.
